Sequence interlock for coke oven door operating valves



Dec. 18, 1962 R. s. COTTON 3,069,022

SEQUENCE INTERLOCK FOR coxs OVEN DOOR OPERATING VALVES Filed Nov. 10,1961 3 Sheets-Sheet 1 I INVENTOR. Poazszrqicorro R. S. COTTON Dec. 18,1962 SEQUENCE INTERLOCK FOR COKE OVEN DOOR OPERATING VALVES Filed Nov.10, 1961 3 Sheets-Sheet 2 R. S. COTTON SEQUENCE INTERLOCK FOR COKE OVENDOOR OPERATING VALVES Filed NOV. 10, 1961 5 Sheets-Sheet 3 1 NV TOR.fiaszr i ov-w a 99 a 33 a United States Patent 3,069,022 SEQUENCEINTERLOCK FOR COKE OVEN DOOR OPERATING VALVES Robert S. Cotton,Pittsburgh, Pa., assignor to Koppers Company, Inc., a corporation ofDelaware Filed Nov. 10, 1961, Ser. No. 151,528 Claims. (Cl. 212-4) Thepresent invention relates to coke oven door manipulating mechanism, andmore particularly to a simpler more economical and facile mechanicalmeans for interlocking fluid pressure actuated operating mechanisms,such as, the conventional hydraulic mechanisms which actuate theoperating means for grasping and unlocking coke oven doors in latchedposition at the end of a coke oven door frame, for withdrawing the door,for turning it to one side for cleaning, and for the reversal of theseoperations after the coke has been pushed and the oven chamber refilledwith coal for a next coke charge. All of these operations are in generalwell known and shown and described in Paul H. Lavely, US. Patent2,576,126 of November 27, 1951.

The hydraulic actuating mechanisms for effecting the actuation of theaforesaid coke oven door operating mechanisms entail the manipulation ofthree levers for operating three hydraulic valve mechanisms in aspecific series or sequence of steps, and requires the conjoint use of amechanical interlocking device for ensuring sequentially a mechanicalinterlock of the hydraulic actuating mechanisms during the respectivehydraulic operations of the various hydraulically actuated operatingmechanisms.

In the prior art, it has been necessary:

(1) To lock the levers which sequentially operate the hydraulic flowcontrol valves in one position by two lock plates;

(2) To release a first lever for a first actuating valve, the operatorhas to lift a handle which lifts a latch that prevents a second leverfor a second actuating valve from being shifted until after the firstlever has been shifted to a position 3;

(3) When the first lever is shifted to position 3, a pin attached tothis first lever allows the latch to be lowered by means of a cam;

(4) The lowering of the latch by means of the cam unlocks a pin attachedto the second lever allowing the second lever to be moved from aposition 1 to a position 3;

(5) The second actuating valve is lifted in position 3 and the firstvalve lever is moved from position 3 to a position 1. By doing this, thelatch is lifted by means of the cam and locks the second lever for thesecond actuating valve in its position 3;

(6) The lock plates and handle will not fall back into locking positionuntil both levers for both actuating valves are in position 1;

(7) In position 2, a lull condition prevails in which all the hydraulicvalve openings are closed.

This prior art system has the disadvantage that: the handle can be tiedback in an unlocked position manually by the operator of the machine;the pins and latch can be bent out of shape, thus making theinterlocking device inoperative; and the interlocking device can only beused on two levers for two valves at a time.

Objects and advantages of the present invention of a simplerinterlocking system for this same purpose are that: only one valveoperating lever can be moved at a time manually by the operator of themachine; a single sliding locking plate is used in conjunction with theoperating levers so that it slides automatically into lever lockingposition and cannot be tied or held back out of operation by the manualoperator of the machine; no

locking recesses.

levers or pins are used which can be bent, which would make themechanism inoperative; and two or more hydraulic valves can be operatedin sequence.

Accordingly, the invention comprises a fixed guide plate immovablerelative to a series of two or more of the operating levers projectingthrough a series of guide slots therefor in the fixed plate, and arelatively movable interlocking plate superimposed, preferably beneath,the fixed plate and likewise provided with a series of guide slotsencompassing the operating levers.

The guide slots in the movable interlocking plate are each provided witha cam portion to be sequentially engaged by their levers for successiveincremental movements of the plate in one direction when the levers aresequentially moved in one direction, to a first position, and each slotis also provided with a cam portion to be engaged by their levers forsuccessive increments of movements of the plate in an opposite directionwhen their levers are sequentially moved in another direction to a thirdposition.

The guide slots in the movable interlocking plate are each also providedwith a locking recess for their levers so arranged relative to the slotsthat the locking recess of a first slot locks its lever upon operationof the second lever, after the locking recess of a second slot has beenunlocked from its lever by the operation of the lever in the first slot,upon successive sequential movements of the levers to their first valveoperating position; and when the levers are moved in succession in areverse sequence to their third valve operating position, the lockingrecess of the second slot again locks its lever as a result of themovement of the lever in the first slot to its third position, leavingthe locking recess of the first slot unlocked as to is lever, as aresult of the successive movements of the plate in the oppositedirection.

Thus, the locking recess of the second slot unlocks its lever only aftera first movement of the plate by the lever in the first slot and thelocking recess for the first locks its lever on the second movement ofthe plate in one direction with movement of the levers sequentially to afirst position, and when the plate is moved in the other direction, thelocking recess for the first slot does not lock its lever, while thelocking recess for the second slot locks its lever, with sequentialmovement of the levers to the third position.

The second slot for the ram lever has its locking recess in the secondposition of lull for this lever and this lever is spring-centered toreturn to the lull position whenever the manual operator of the machinereleases his handheld on this lever.

The third slot in the plate for actuating the door hook for holding thedoor on the ram, is provided with two The first locking recess is tolock the third lever in the first position when the first turn lever isin its first position and the second ram lever is in its third position.The second locking recess is to lock the third lever in the thirdposition while the first two levers are in their third position. Thefirst locking recess is in a position to lock the door hook operatinglever in the first position at which the door holding hook is detachedfrom the door while the door is in place on an oven door frame and thedoor latches are released to latch the door in place in its door frame.The second locking recess is in a position to lock the door hook operating lever in the third position at which the door hook holds thedoor on the ram and the door latches released from latching relationwith the door frame.

The invention, as disclosed and claimed hereinafter, while primarilydesigned and adapted for manipulating the door handling mechanism forthe coke side doors of coke ovens, is not limited in all its aspects tothis use and best mode of embodying of the invention, since the novelfeatures of invention are also equally applicable to other equipmentsuch as, for instance, interlocking the operating levers for the drivingmechanism for moving the door machine carriage from oven chamber to ovenchamber, as well as, also for interlocking the levers for the operatingmechanism for moving the coke guide into and out of guiding relationwith the door frames of the coke oven chambers. The invention is alsoapplicable, for instance, to interlocking of the pusher side controllevers, including the levers for the operating mechanisms for advancingthe pusher ram on the pusher side of the battery into the oven todischarge the coke, and also those for levers for operating the carriagefor moving the pusher ram along the pusher side of the battery from ovenchamber to oven chamber.

The invention will appear more clearly from the following descriptiontaken in connection with the accompanying drawings in which:

FIGURE 1 is a top plan view of a valve interlocking block systemembodying the invention with three operating levers for three sets offour-way hydraulic control valves therein;

FIGURE 2 is a side elevational view of the same;

FIGURE 3 is a top plan view of the interlocking sliding plate shown indotted lines in FIGURE 1;

FIGURE 4 is a top plan view on a smaller scale of the fixed cover plateshown in full lines in FIGURE 1 superimposed over the interlockingplate;

FIGURES 5 to are top plan views of the fixed cover plate with theinterlocking plate in phantom lines beneath the same to show thesequence of operating the levers from starting position of the threelevers, in FIG. 5, to the finish of the complete cycle of operations, inFIG. 10, for replacing a coke oven door from its 90 turned position forcleaning to its latched condition on a coke oven door frame, thenremoving the door from the door frame and again restoring it to itsstarting position for cleaning of the self-sealing edges of the door;

FIGURE 11 is an elevational view with parts in section illustrating thepreferred form of door handling or manipulating machine of the inventionas applied in lifting and unlatching a coke over door from its doorframe on one oven chamber of a battery of horizontal coking retort ovenchambers; and

FIGURE 12 is a diagrammatic view illustrating the hydraulic fluidpressure flow lines typical for each operating lever and its set offour-way valves to and from a hydraulic fluid pressure piston cylinderfor actuating one of the door operating means, the view being of thecontrol system for the cam lever for operating the door lifting hook.

The same reference characters indicate the same parts in each of theseveral view of the drawings.

The interlocking mechanism is primarily designed for and adapted to theautomatic operation of door handling machines for horizontal cokingchambers as in the general manner exemplified in Lavely, US. Patents2,335,866; 2,335,867 and 2,576,126.

In such environment as will be seen from FIGURE 11, the door handlingmachines for opening and closing the doorways of the coking chambers iscarried on a truck 20 that is propelled alongside a battery 21 of thecoking chambers, one of which 22 is shown in section with a door 23 inplace on a door frame (not shown). The door is provided with upper andlower hooks 24 to be lifted by the door lifting hooks 25 on the doormachine truck 20. The door handling machine comprises a ram or acarriage 26 movable on wheels 26 transversely of the truck into and outof door seating and door unseating relation with the doorways at thehorizonal ends of the respective side by side coking chambers 22 of thebattery.

The ram or carriage 26 is provided with operating means in the form oflinks 27 and bell crank levers 28 for advancing the carriage forwardlytowards the battery to seat and unseat the doors in the doorway andbackwards from the battery side to carry the door away to one side ofthe chamber 22, when opening the chamber for pushing out of coke cakesthrough the doorway, or for removal of the rain or machine from the doorafter replacing a door on the chamber 22 and then shifting of the ram ormachine along the battery side to the next door to be removed.

This ram or carriage 26 is mounted on a post or holder mechanism 29 thatis pivotally mounted at 30 on the truck 20 to be turned ninety degreesto one side of the doorway by operating means in the form of a levermechanism 31 at the top of post 29 after the door is retracted from theoven, for the purpose of cleaning the door seals before restoring thedoor onto the oven chamber doorway.

The ram or carriage 26 also carries a raisable and lowerable door liftermechanism 32 containing the upper and lower door lifting hooks 25 forgrasping or holding the door while the ram or carriage 26 is advancingand retracting the door 23 and while the door is turned for cleaning,all as hereinafter described and as discussed in greater detail in saidLavely patents aforesaid. The door lifting mechanism 32 is raised andlowered by operating means in the form of a crank lever 33 and linkage34.

By means (FIG. 12) of hydraulic fluid pressure from a pump line 35 andtank line 36 and three sets of four-way valve mechanical connectionsinside the block 40 and intervening between three hydraulic cylinders37, 38, 39, the aforesaid reverse movement of these three componentparts of the door handling machinery is effected under the control ofthe three sets of four-way valves and three valve operating levers 41,42, 43, therefor. These are all contained in the valve block 40 with atable mounted on the truck 20 that carries the door handling mechanismfrom chamber to chamber along the battery. It is from this table that anoperator operates all the operations of the truck 20 and door handlingmechanisms. One set of valves and its operating lever 41 controls thehydraulic cylinder 37 for turning the door through an arc of 90 degrees.A second set of these valves and their operating lever 42 controls thehydraulic cylinder 38 for the forward and backward movements of the ram.The third set of valves and their operating lever 43 controls thehydraulic cylinder 39 for holding and release of the door holding orgrasping hook elements 25 for lifting the coke oven doors 23 of thedifferent coking chambers 22.

Each valve set is arranged to direct the hydraulic fluid pressure fromthe pump line 35, through a line 37, 38 or 39, to one end of itshydraulic piston cylinders 37, 38 or 39, and to exhaust the hydraulicfluid pressure therefrom through a line 37 38 or 39* from the other endof the piston cylinder to supply the tank line 36 for supply ofhydraulic fluid back to the pump line 35, when the operating levers orrods 41, 42, or 43 are moved to forward 1 position, and when itsoperating lever or rod 41, 42, 43, is moved to the rearward 3 position,the valve set directs the fluid pressure from the pump line 35 to theother end of the hydraulic piston cylinder through the lines 37 38 or 39and exhausts the fluid pressure from the opposite end of the pistoncylinder through the lines 37*, 38 or 39 to the supply tank line 36 forthe pump. In the middle 2 position of the rods or operating levers, thevalve lines aforesaid are cut off from both the pump line 35 and fromthe exhaust line 36 to the supply tank.

The turn lever 41 when moved to the first position 1 controls thehydraulic valves for flow of hydraulic pressure to line 37 to turn thecoke oven door from a turn position for cleaning the door to an in tooven position for closing the coke oven chamber doorway, and when thefirst turn lever 41 is moved to its third position 3, it controls thehydraulic valves for flow of hydraulic pressure to line 37 to turn thedoor back again into its 90 turn out position for cleaning the doorseals. The second ram lever 42 when moved to the first position 1controls the hydraulic valves for flow of hydraulic pressure to line 38to advance the door in to oven, and when the second ram lever 42 ismoved to its third position 3 it controls the hydraulic valves for flowof hydraulic pressure to line 38 to retract the door seating ram out forwithdrawing a coke oven door out of a coke oven doorway or to withdrawthe ram without the door thereon, leaving the door in latched conditionon a coke oven chamber. The third, a hook lever 43 when moved to thefirst position 1 controls the valves for flow of hydraulic pressure toline 39 to actuate the door liftinghooks 25 on'the door machine to lowerthem to a hooks down position for releasing or ungrasping the coke ovendoor, and when the third hook lever 43 is moved to its third position 3it controls the hydraulic pressure for flow to line 39 to actuate thehooks 25 to up position for grasping and holding the door on the ram 26.The three levers 41, 42, 43 are each movable to a middle lull position 2in which all the four-way hydraulic valves are closed off from theirfluid pressure lines. The turn lever 41 when moved forward to in to oventurns the door from a 90 turned aside position for cleaning to a forwardposition for seating the door in a coke oven chamber. The turn lever 41when moved rearward to out turns the door aside 90 for cleaning. The ramlever 42 when moved forward to in to oven operates the ram 26 to movethe door 23 in to its seating position on a coke oven door frame, or tomove the ram in to grasp and take off a door, and when moved rearwardlyto out position operates the ram to withdraw the ram 26 with or withoutthe door 23 suspended on the hooks 25 thereon, depending on the 1 or 3position of the hook lever 43. The hook lever 43 when moved forwardoperates the bell crank 33 which operates door hooks 25 to. releasetheir grasp and lift on coke oven door suspended on the ram and operatesthe door latches 44 into the door frame hooks, not shown. This hooklever when moved rearward operates the bell crank 33 to cause the doorhooks 25 to grasp and lift the door 23 and release the latches 44 fromholding engagement from a coke oven door frame. Only the ram lever 42 isspring centered to return the ram lever 42 to the middle position 2whenever the operator removes his hand from the ram lever, thus leavingthis lever free to be moved forward to ram advancing position orrearward to ram retracting position whenever the need arises unless theram lever is locked.

In accordance with the invention, an interlocking plate 45 is slidablymounted inside the block 40 with the lever 41, 42, 43 projecting throughthree slots 46, 47, 43. This plate is then covered with a fixed plate 49having three parallel slots through which the levers project. The plate45 is provided with the following parts as seen in FIG. 3.

(1) A part 50 in the formof a cam along the region of the turn leverguide slot 46, in the path of movement of the turn lever 41 from itsmiddle lull position 2 to its forward position 1, for shifting theinterlocking plate 45 to a position at which a locking part 54 for theturn lever 41 in its 1 position is moved an increment closer to the lineof movement of the turn lever 41 but does not intercept the latter, anda locking part 55 for the ram lever 4'2 unlocks this lever 42, and twolocking parts 56 and 57 for the hook lever 43 have shifted one incrementbut still continue to lock the hook lever, either in its rearward doorholding position 3 or in its forward door unhooking position 1. Theselocking parts are recesses in the locking plate offset from the guideslots.

(2) A part 52 in the form of a cam along the region of the ram leverguide slot 47 in the path of movement of the ram lever 42 from itsmiddle position 2 to its forward position 1, for shifting theinterlocking plate 45 another increment to a further position at whichthe locking part 54 for the turn lever 41 intercepts it and locks it inits 1 position, and the two locking parts 56, 57 for thehook lever 43are shifted another successive increment to unlock the hook lever. Atthis time, the

' 6 hook lever 43 can be moved either to its forward position 1 at whichit causes the door lifting hooks 25 to release the door and the doorlatches 44 to move into latch hooks on the door frame, or to its rearposition '3 to lift the door hooks 25 to grasp and hold the door 23 andto simultaneously unlatch the door latches 44 from their door framehooks.

(3) A part 53 in the form of a cam along the region of the ram leverguide slot 47 in the path of movement of the ram lever 42 from itsmiddle position 2 to its backward position 3, for shifting theinterlocking plate one increment in the opposite direction to a positionat which the hook lever 43 is locked either in its forward position 1 bythe forward hook lock part 56, or is locked in the rearward position 3by the rearward lock part 57, and the turn lever is unlocked by itsforward lock part ready for the next turn operation.

(4) A part 51 in the form of a cam along the region of the turn leverguide slot 46 in the path of movement of the turn lever 41 from itsmiddle position 2 to its backward position 1, for shifting theinterlocking plate 45 another successive increment still further in saidopposite direction to a position at which the ram lever 42 is locked inits middleward position 2 by its lock part 55, the hook lever 43 iscontinued to be locked by either its forward lock part 56 or itsrearward lock part 57, and the lock part 54 for the turn lever 41 isshifted a further increment away from the line of movement of the turnlever 41 in the turn slot 46.

The operation of the mechanical hydraulic interlock appears from thefollowing description of FIGURES 5 to 10:

FIG. 5-Starting position shows turn lever 41 in center position and isfree for the first operation. This lever is not spring-centered. The ram42 and hook 43 levers are locked in the 2 and 1 positions as shown.

FIG. 6Step No. 1 shows turn lever 41 moved forward to 1 and at the sametime unlocks ram lever 42. Hook lever 43 is still locked at 56.

FIG. 7-Step No. 2 shows ram lever 42 moved forward to 1 and at the sametime 42 unlocks hook lever 43 and 54 locks turn lever 41. The ram leveris springcentered and will come back to center position 2 when operatorremoves his hand from the lever.

FIG. 8Step No. 3 shows hook lever 43 moved backwards to 3, ram lever 42ready for next operation and turn lever locked. Hook lever is notspring-centered.

FIG. 9-Step No. 4 shows ram lever 42 moved backwards, hook lever 43locked at 57 and turn lever 41 unlocked at 54, ready for the nextoperation.

FIG. lO-Step No. 5 shows turn lever 41 moved backwards to 3, ram 42 andhook 43 lever locked at 55 and 57.

In the above operation, the operator moves one valve lever at a time.The locking plate 45 slides automatically into position and cannot betied or held back out of operation. No levers or pins are used and hencecannot be bent, which would make mechanism inoperative. Two or morevalve levers can be operated in sequence.

The invention as hereinabove set forth is embodied in a particular formand manner but may be variously embodied within the scope of thefollowing claims.

I claim:

1. In a coke oven apparatus for sequentially manipulating a self-sealingcoke oven door in removing it from and replacing it in a door frame forthe door on'a coke oven chamber, said apparatus having turn operatingmeans to turn the door to an out position for cleaning and to an inposition facing the door for sealing in the door frame, ram operatingmeans to move the door to an out position away from the door frame andto an in position for closing the doorway of the door frame, and lifteroperating means to move door lifting and latching means to gripping andunlatching relation with the door on the door frame and to grip releaseand latching relation with the door, the combination of a series ofindividual actuating means for actuating each of said turn, and ram andlitter operating means, each of said actuating means including amanually manipulative member movable to a middle position for lull ofthe respective actuating means, and movable to an in position and to anout position for operating the actuating means to actuate the respectiveoperating means to their respective positions, and an interlocking platemounted for movement relative to said three manually manipulativemembers and provided with a series of guide slots encompassing saidmembers, at least two of the guide slots for the manipulative membersfor the turn and ram operating means being each provided with a camportion to be sequentially engaged by their members for successiveincremental movements of the plate in one direction, to said inposition, and each slot also being provided with a cam portion to beengaged by their members for successive increments of movement of theplate in an opposite direction when their members are sequentially movedin another direction to said out position, each of said two slots alsobeing provided with a locking recess for their members so arrangedrelative to the slots that the locking recess of the turn member slotlocks its member upon operation of the ram member in its slot after thelocking recess of the ram member slot has been unlocked from the rammember by the operation of the turn member in the turn member slot uponsuccessive sequential movements of the members to their in positions,the locking recesses also being so arranged relative to said two slotsthat when the manipulation members in the slots are moved in successionin reverse sequence to their out position the locking recess of the rammember slot again locks its member as a result of the movement of theturn member in the turn member slot to its out position, leaving thelocking recess of the turn member slot unlocked as to its member, as aresult of the successive movements of the interlocking plate in theopposite direction, the third slot of said three slots being providedwith two locking recesses, one at the in position and the other at theout position for the manipulative member for the lifter operating means,said locking recess locking the lifter member during the successive outmovements of the turn and ram members and unlocking the lifter memberonly after completion of the successive movements of the turn and rammembers to their in position.

2. In coke oven apparatus for sequentially manipulating a self-sealingcoke oven door in removing it from and replacing it in a door frame forthe door on a coke oven chamber, said apparatus having turn operatingmeans to turn the door to an out position for cleaning and to an inposition facing the door for scaling in the door frame, ram operatingmeans to move the door to an out position away from the door frame andto an in position for closing the doorway of the door frame, thecombination of a series of individual actuating means for actuating eachof said turn and ram operating means, each of said actuating meansincluding a manually manipulative member movable to a middle positionfor lull of the respective actuating means, and movable to an inposition and to an out position for operating the actuating means toactuate the respective operating means to their respective positions,and an interlocking plate mounted for movement relative to said manuallymanipulative members and provided with guide slots encompassing saidmembers, the guide slots for the manipulative members for the turn andram operating means being each provided with a cam portion to besequentially engaged by their members for successive incrementalmovements of the plate in one direction, to said in position, and eachslot also being provided with a cam portion to be engaged by theirmembers for successive increments of movement of the plate in anopposite direction when their members are sequentially moved in anotherdirection to said out position, each of said slots also being providedwith a locking recess for their members so arranged relative to theslots that the locking recess of the turn member slot locks its memberupon operation of the ram member in its slot after the locking recess ofthe ram member slot has been unlocked from the ram member by theoperation of the turn member in the turn member slot upon successivesequential movements of the members to their in positions, the lockingrecesses also being so arranged relative to said slots that when themanipulative members in the slots are moved in succession in reversesequence to their out position the locking recess of the ram member slotagain locks its member as a result of the movement of the turn member inthe turn member slot to its out position, leaving the locking recess ofthe turn member slot unlocked as to its member, as a result of thesuccessive movements of the interlocking plate in the oppositedirection.

3. Coke oven apparatus as claimed in claim 2 and which includes ahousing for said actuating means including said interlocking plate, andwhich includes a fixed cover plate provided with a correspondingplurality of guide slots through which said turn and ram members projectfor access from outside the housing for manipulation of the actuatingmeans, said fixed cover plate concealing the interlocking plate fromunwarranted alteration by an attendant operating the members.

4. Coke oven apparatus as claimed in claim 2 and in which the ram memberis spring-centered to always return to its middle position when themember is released from the hand of an attendant operating the same, andin which the locking recess for the ram member locks the same asaforesaid in said middle position.

5. Apparatus for sequentially interlocking the manipulation of a cokeoven door adapted to be removed and replaced from the door frame of acoke oven chamber by means of ram means with door lifting and holdingmeans for releasably holding the door on the ram, and turn means forturning the door to one side while held by the door holding means on theram, comprising: a valve block system with three operating levers eachmovable to a forward position, a backward position and a middleposition, and valve means operable thereby to effect the aforesaidoperations of the aforesaid means with reversal of said operations, andmeans for insuring a predetermined sequence of said operationcomprising, a sliding interlocking plate concealed in said block andhaving three guide slots through which said levers extend, formanipulation exteriorly of said valve block, the slot for the turn leverhaving a part operable by the turn lever in its movement from middleposition to forward position for shifting the plate a single incrementof movement in one direction, and a locking part at the forward positionfor locking the turn lever there upon two increments of movement of theplate in said one direction by the turn and ram levers, the slot for theram lever having a part operable by the ram lever in its movement frommiddle position to forward position for shifting the plate a secondsuccessive increment of movement in addition to the one increment ofmovement by the turn lever, said ram slot having a locking part forlocking the ram lever in middle position until the aforesaid singleincrement of movement by the turn lever, the slot for the door holdingmeans lever having two locking parts, one at the forward position andone at the backward position of the lever in said door holding meanslever slot, for locking the lever in the slot during the two incrementalmovements of the plate by the turn and ram levers, said turn and ramlever slots also having a part operable by the levers therein in theirmovements from middle position to backward position for shifting theinterlocking plate two increments of movement in the opposite direction.

Lavely Nov. 27, 1951 Peregrine July 29, 1952

